Stoker



May 20, 1941.

w. o. MARTIN l sTokER Filed April 20, 1939 5% N .www

Patented May 20, 1941 UNITED STATES PATENT OFFICE STOKER William 0. Martin, Fort Smith, Ark. Application April 20, 1939, Serial No. 268,949

(Cl. 835Z) 5 Claims.

My invention relates to mechanical stokers for use with the lire-boxes of boilers and more particularly to stokers for locomotives and the like, whereby the fuel or coal may be introduced through the usual fire-door opening in the back wall of the nre-box, or by means of a vertical riser located inside of the dre-box.

The invention contemplates a horizontally disposed trough, for receiving the coal,dconnect ed with one end of a conduit, a conveyor screwshaft extending lengthwisely of the trough and conduit; a riser extending upwardly from the .forward end of the conduit and terminating in a receptacle adapted to be secured tothe back wall of the fire-box' about the firing or door opening and provided with a distributing table which is adapted to extend through the firing opening in the back head of the fire-box.

My invention involves the provision of means for breaking or reducing the coal below a predetermined size before it is conveyed into the conveyor conduit and discharged onto the distributing table; said means being adapted to break the coal into 'smaller pieces through the action of elements which subject the coal to hammer-like blows and the broken coal then forced through a stationary grille or grate which prevents coal larger than the lpredetermined size passing into the conveyor portion of the Stoker.

Another object of the invention is the provision of a simple and effective means for preparing and conveying the fuel from -the supply end of the stoker to the delivery end; whereby delivery is made through an upwardly disposed l conduit portion or riser without the need for special lifting mechanism; and whereby a minimum amount of power is required for operation of the stoker and the weight of the stoker equipment materially reduced.

The foregoing enumerated objects as well as others, and the advantages inherent in the invention will all be readily comprehended from the following detailed description of the accompanying drawing wherein:

Figure 1 is a top plan view of my improved Stoker shown applied to the rear end of a flrebox of which only a portion is shown.

Figure 2 is a transverse sectional view taken on the line 2-2 of Figure 1, looking in the direction of the arrows.'

Figure 3 is a longitudinal sectional view of my improved stoker mechanism with only a portion of the receiving trough and the riser portion being shown.

y tion I9b Figure 4 is a perspective view of one of the coal breaking elements.

My improved stoker, although applicable for use with a stationary boiler, is more especially adapted for use with a locomotive nre-box and is intended to be applied to the rear wall of a locomotive fire-box.

The stoker mechanism involves a suitable trough I1 which generally is mounted beneath an opening in the deck of'a locomotive tender so as to receive the coal therefrom; the forward 6r delivery endof the trough communicating with a removable housing or shellv I8 whose opposite side wall is removably connected with a section I9 of a preferably sectional conveying conduit; the various sections I9, |93 and I9b being shown connected by ball and socket joints as at 20. The forward section Iiih has an opening in its top which communicates with an upwardly disposed riser portion 2| which in turn lcommunicates with a receptacle 22 disposed about the door-opening and suitably secured to the back wall of the fire-box. The forward secof the conveying conduit extends slightly forward of the riser portion 2| and has one end wall, see Figure 3, which may provide a bearing for the forward section or end of a sectional conveyor shaft consisting of sections 23, 23a and 23"; the respective sections being connected together by suitable universal joints. The sectional conveyor shaft, (which extends from rear to front in a substantially horizontal plane) in the particular exemplifl'cation, is driven through the medium of suitable gearing located in the gear housing at the rear end of the trough and shown in dotted lines at 24 and 25 in Figure 1; gear 25 being secured to a drive. shaft 26 arranged along th`e side of the stoker mechanism and provided with suitable universal joints 21 and 28; the shaft being driven by any suitable motor as indicated at 29 and which may be mounted beneath the oor,v of the locomotive cab.

The drive shaft 26, at a point coincident with the housing or shell portion I8 of the stoker conduit. is shown provided with a bevel gear 30 meshing with a bevel gear 3| secured on a stubshaft provided with a gear 32 which meshes with a gear 33 mounted on a. shaft 34 disposed through the shell I8 transversely of the sectional conveyor shaft. 'I'he transverse shaft 34 in the particular exempliiication is shown in a plane above f that of the sectional conveyor shaft although it may be in a plane beneath if found advisable. The gears just mentioned are preferably located incoming coal delivered from trough in an extension of the shell I8 through which the drive shaft 26 extends.

The portion of the conveyor shaft 23 located within the shell I8 is formed without its thread or spiral; that is to say, the screw thread vor spiral at the forward end of section 23 is preferably interrupted. The body portion of shell I8 is preferably trough shape, see Figure 2, and is provided with a plurality of spaced apart upstanding |bars 35 which are suitably secured to the bottom of the shell I8 and extend upwardly above the horizontal medium line of the shell and hence above the horizontal plane of the conveyor shaft section 23. 'I'hese upstanding bars or grate elements 35 are apertured to provide suitable bearing for the transverse shaft 34, while the intermediate upstanding bar 36 is formed to provide a suitable bearing or support for the section 23 of the conveyor shaft, see Figure 2.

The shaft 34, at spaced apart points, is provided with a plurality of lugs 31 secured to the shaft 34 so as to rotate therewith, and the ends of the lugs formed with forwardly presented prongs or teeth with tapering surfaces whereby more or less sharp edges are presented to the coal delivered into the shell portion .I3 from the trough I1. These lugs, in view of the troughlike shape of the shell portion I8, are shown of different lengths and the bars may have their rear sides also formed to present more or less sharp surfaces or edges to the oncoming coal. The various lugs may all -be of the general construction shown in Figure 4 or may have a plurality of teeth if desired.

The transverse shaft 34 is intended to rotate in a direction which will cause the toothed lugs to rotate in the general direction of flow of the I1, and subject the coal to a series of hammer-blows while at the same time urging the |broken coal forwardly through the bars. Where the lumps of coal are of size greater than the size determined by the spacing of the bars, the lumps will be subjected to a series of hammer-blows delivered by the constantly revolving toothed lugs; the brokencoal then being forced through the bars by the revolving lugs and into contact withA the adjacent conveyor screw section which carries it to the lower end of the riser 2l. With my improved mechanical coal breaking means, the coal will all be lreduced below a predetermined size.

firing lbefore it is introduced into the conveying conduit, without, however, subjecting Vthe coal to a crushing action which results in the coal being broken into dust form or' into such fine particles that the fuel is apt to be carried through the nre-box and into the smoke-stack in unburned condition, resulting in an undesirable fuel loss.

The lugs 31 are preferably secured totransverse shaft 34 in line with each other as shown. With my improved means the coal is subjected to hammer-like blows by the rotating lugs and in commotion with the stationary bars causes the coal, which is of larger size than the spacing between the bars, to -be reduced in size and forced forwardly to 23 in conduit I9; the method eliminating some of the difficulties encountered with stokers as suitable for proper heretofore constructed wherein the coal was subjected to a squeezing or crushing action by means of the conveyor screw and a reduced conduit or throat. Such method not only requires a varying sized conduit section but also requires greater power in driving the conveyor screw whereby the conveyor screw section the coal is crushed into undesirable fine particles or dust which permits a large percentage thereof to be carried, in an unconsumed state, into the smoke-stack. In my improved stoker, the coal is not subjected to a crushing or squeezing action and the lumps of coal which are larger than the desired size determined by the spacing between the stationary bars, are merely broken into smaller lumps without complete disintegration.

In operation, the coal drops by gravity from the tender into the open top of the trough and is conveyed forwardly by section 23 of the conveyor which extends continuously to the forward end of the stoker mechanism. The conveyor section 23 carries the coal to the coal breaking chamber or conduit section I8, where further travel or movement of the fuel is induced by the rotating hammer-lugs which force the fuel between the grate-bars and into the'initial end of conduit section I3 where it comes\into engagement with the screw-conveyor and is carried forwardly.

The stoker mechanism lwith its continuous conveyor shaft and coal4 breaking mechanism is operated by any suitable motor through the medium of a single drive shaft; suitable connections or universal joints being employed to compensate for deviations and the relative "movements between the tender and the fire-box end of the locomotive; and while I have described the invention as especially adapted to a locomotive fire-box,'it` is apparent that the invention is not confined to such adaptation.

What I claim is:

l. A stoker of the character described comprising a coal receiving trough; a longitudinally disposed conduit; a shell for connecting the conduit with the delivery end of the trough; a screw conveyor disposed lengthwisely through the trough, said shell and the conduit and the portion within said shell provided with an interrupted thread; vertically disposed bars arranged in laterally spaced relation in Asaid shell; coal hammer-ing means located in said shell and arranged to rotate between and on opposite sides of said bars; and means for rotating the screw conveyor and said coal hammering means.

2. A stoker of the character described comprising a coal receiving trough; a longitudinally dis'- posed conduit provided with an enlarged end connected with said trough; a screw conveyor disposed lengthwisely through the trough and the conduit `and having an interrupted thread at the enlarged end portion of the conduit; vertically` disposed bars arranged in spaced relation transversely of the bottom of said enlarged end of the conduit; a rotatable shaft disposed transversely intermediate of the top and the bottom of said enlarged end and supported by said bars; a plurality of lugs, provided with forwardly tapered coal engaging surfaces, secured to said shaft in spaced relation so as to pass between said bars; and means for rotating the screw conveyor and said rotatable shaft.

3. In a stoker, a coal receiving trough; a conduit connected with one end of said trough; screw conveyor means for 'feeding the coal lengthwisely of Ethe trough and the conduit; means arranged transversely of the conduit for preventing the yforward movement of coal larger than a predetermined size, said means involving spaced apart non-movable elements extending upwardly from the bottom of the conduit into a plane above the axis of the conveyor means 2,242,587 and spaced apart hammer elements arranged to rotate about an axis disposed transversely of said conveyor means and adapted to pass between the non-movable elements whereby the coal is subjected to hammer-like blows and the broken coal forced beyond the. non-movable eleverse shaft-and the conveyor screw may be rotated at predetermined speeds.

5. In a stoker of the character described; a

' conduit; a screw conveyor disposed lengthwise ments; and means for rotating the conveyor elements at predeterandinvclving a transversely disposed revolvable shaft provided with hammer-blow imparting elements adapted to rotate on opposite sides of the' axis of the conveyor screw and to force the broken fuel forwardly: and a drive shaft having geared 'connections with said transverse shaft and withrthe screw conveyor whereby the trans-Y of and in contact with the bottom of the conduit; means whereby positive forward movement `of the fuel is interrupted and the furthertmove ment of fuel larger than a predetermined size prevented, said means involving a shaft disposed transversely of and above thescrew conveyor and a' plurality of spaced apart elements secured to said transverse shaft to rotate therewith and to extend into predeterminedkproximity with the bottom of the conduit adapted to subject the fuel to hammer-like blows and to force the brokenfuel forward; means whereby the screw conveyor is rotated; and means operatively intermediate of said last mentioned means and said shaft whereby the latter is rotatedat a prearranged speed relative to the speed of the screw conveyor.

, WILLIAM O. MlilfI'IN.` 

